As someone pointed out last year, a lot of the places with a high proportion of people living to a very old age also have disproportionately low numbers of people dying in their 80s and 90s, poor record keeping, and tough economic conditions that motivate people to bump up their ages to collect their pensions earlier. In Japan in particular, clusters of supercentenarians correlate with places where birth registries were destroyed in WW2 bombing. I wonder whether this is the case here.